[25] Sprengel (28).
[26] Witham (33).
[27] ibid., p. 3.
[28] Witham (33), p. 5.
[29] Nicol (34). See note by Prof. Jameson on p. 157 of the paper quoted, to the effect that he has long known of this method of preparing sections.
[30] Limpricht (90) in Rabenhorst, vol. IV. p. 73.
[31] Knowlton (89).
[32] Corda (45).
[33] Binney (68), Introductory remarks.
[34] Williamson (71), etc.